aero
The impedance problem is something I discussed with the Crown service guys long ago and they didn't really think it was a problem. I believe their ratings use the term "nominal" and the amps can deal with some fluctuations.
Elliot
Sure. They can handle some fluctuations. However, if the
impedance dips too low its going to cut back the power.
Thats the concept behind ODEP. Instead of shutting down
like the majority of amplifiers do, ODEP will just reduce
the output. Think compression here. The more signal you
feed it, the lower the output is reduced.
aero
However, a single problematic driver is a good idea. I'll have to check all 10 of the cabs I have and that won't be fun.
Elliot
I think some confusion is starting here. The driver is
not defective. Its the way how the driver reacts in the
enclosure. All speakers experience this. This is why
you generally find regional tour companies, playing at
4 ohms per channel in stereo mode minimum. Its to ensure
the amplifier can play under the worse case scenerio,
when you are driving them at volume 11.
To make your life easier, just request the impedance curve
sheet for the LA 460 from EAW. Its a ballpark estimate, and,
will give you a general idea where the LA 460 stands under
the given frequency.
Actually, you would really need to have the proper tools
to literaly measure the impedance curve on how the speakers
corelate in the enclosure.
aero
I figured I wouldn't need the full 2000 Watts out of this amp configuration. The speakers would over-excurt before I reached this output power. That is not happenning. So if ODEP limits the output power can it be cutting by 1000 Watts when hot? Seems unlikely.
Elliot
I agree. Take the old 4 rack space Peavey CS 800 for example.
The spec sheet states 460 watts per channel @ 1Khz, 1% THD.
At 2 ohms per channel, the amplifier wattage reduces to 250
watts. This is because the amplifier is limiting the output
to prevent overheating, and, premature shutdown. In the case
of the MA 2402, the ODEP is doing the same thing.
It will reduce the output low enough so the amplifier won't
shutdown. Whether its 1000 watts or 5 watts, it depends on
how hard you are driving the amplifier when the impedance
of the speakers are dipping below the amplifiers minimum
load, when driven at high SPLs.
aer
The trouble with using them in stereo mode which I did at first was 1 cab, 1 amp channel, i cable. I needed way too much cable and too many amps for this to be a practical system for my jobs. Sure, some 850's or Meyer MSL's but gear and crew and a bigger truck are expensive. I can move and set-up this system nearly alone.
Elliot
I hear dude. I'm a one man army myself. You could operate the
amplifier in Parallel Mono. In this mode, the minimum impedance
is 1 ohm, and, you could load two cabs using one speaker cable.
Keep in mind that Crown's MA/MT/PB/PT/CT/ parallel mono is
not considered what QSC, and, Crest considered parallel mono.
If you refer to the MA 2402's manual, it will tell you
how to configure the amplifier to handle a 1 ohm load.
Using it in this fashion, increases the 2402's current,
thus handling 1 ohm. Oppose the Bridge Mono method, which
increases more voltage, offering 4 ohm minimum.
I can understand the money you've invested in this rig,
and, you can't just upgrade so easily. This is why, I'm
giving you more alternatives.
Best Regards,